Technical Field
Embodiments described herein are related to the field of systems-on-a-chip (SoCs) and, more particularly, to configuration fuses in an SoC.
Description of the Related Art
A variety of electronic devices are now in daily use with consumers. Particularly, mobile devices have become ubiquitous. Mobile devices may include cell phones, personal digital assistants (PDAs), smart phones that combine phone functionality and other computing functionality, tablets, laptops, net tops, smart watches, wearable electronics, etc. Generally, a mobile device may be any electronic device that is designed to be carried by a user or worn by a user. The mobile device is typically battery powered so that it may operate away from a constant electrical source such as an electrical outlet.
Many mobile devices may operate in a “standby” mode much of the time. In the standby mode, the device may appear to be “off,” in as much as the device is not actively displaying content for the user and/or not actively performing functionality for the user. In the standby mode, much of the device may indeed be powered off. In the background, however, the device may be polling voice and data networks, checking for alarms, reacting to movement, etc.
Because mobile devices are often operating from a limited power supply (e.g. a battery), energy conservation is a key design consideration for the devices. A mobile device may include a system-on-a-chip (SoC) as an aid in energy conservation, since much of the functionality needed in the device can be included in the SoC. In “standby” or other low power modes, it is desirable to power down the SoC to eliminate leakage current losses, which are a significant factor in energy consumption in modern integrated circuit technologies.
Some circuits in an SoC may require initialization before they can be fully utilized. In some cases, initialization information may be stored in a non-volatile memory, such as flash, for example, within the system and the SoC may read the information and initialize corresponding circuits accordingly. Some circuits, however, may need to be initialized before an available non-volatile memory is capable of being read. In such cases, one or more configuration fuses may be included within the SoC and used as a non-volatile memory to store initialization information.
When an SoC transitions into reduced power modes, some circuitry of the SoC may be disabled as part of the power reduction. Disabling circuits may result in configuration information for the circuits being reset and requiring re-initializing when the circuits are enabled. Re-initializing the circuits may require reading fuse values to get the initialization information.